mir-181A/B-1 controls thymic selection of treg cells and tunes their suppressive capacity

The interdependence of selective cues during development of regulatory T cells (Treg cells) in the thymus and their suppressive function remains incompletely understood. Here, we analyzed this interdependence by taking advantage of highly dynamic changes in expression of microRNA 181 family members miR-181a-1 and miR-181b-1 (miR-181a/b-1) during late T-cell development with very high levels of expression during thymocyte selection, followed by massive down-regulation in the periphery. Loss of miR-181a/b-1 resulted in inefficient de novo generation of Treg cells in the thymus but simultaneously permitted homeostatic expansion in the periphery in the absence of competition. Modulation of T-cell receptor (TCR) signal strength in vivo indicated that miR-181a/b-1 controlled Treg-cell formation via establishing adequate signaling thresholds. Unexpectedly, miR-181a/b-1–deficient Treg cells displayed elevated suppressive capacity in vivo, in line with elevated levels of cytotoxic T-lymphocyte–associated 4 (CTLA-4) protein, but not mRNA, in thymic and peripheral Treg cells. Therefore, we propose that intrathymic miR-181a/b-1 controls development of Treg cells and imposes a developmental legacy on their peripheral function

Extra-Thymic Physiological T Lineage Progenitor Activity Is Exclusively Confined to Cells Expressing either CD127, CD90, or High Levels of CD117

T cell development depends on continuous recruitment of progenitors from bone marrow (BM) to the thymus via peripheral blood. However, both phenotype and functional characteristics of physiological T cell precursors remain ill-defined. Here, we characterized a putative CD135+CD27+ T cell progenitor population, which lacked expression of CD127, CD90, and high levels of CD117 and was therefore termed triple negative precursor (TNP). TNPs were present in both BM and blood and displayed robust T lineage potential, but virtually no myeloid or B lineage potential, in vitro. However, TNPs did not efficiently generate T lineage progeny after intravenous or intrathymic transfer, suggesting that a physiological thymic microenvironment does not optimally support T cell differentiation from TNPs. Thus, we propose that physiological T cell precursors are confined to populations expressing either CD127, CD90, or high levels of CD117 in addition to CD135 and CD27 and that TNPs may have other physiological functions

Verbleib von Soziologie-AbsolventInnen der Philipps-Universität Marburg

Soziologie ist an der Philipps-Universität in den 1960er Jahren als akademisches Studienfach entstanden und ab 1972 ausgebaut worden. Neben den beiden Kernbereichen 'Soziologische Theorien' und 'Methoden empirischer Sozialforschung' konnten Studierende Ende der 1990er Jahre zwischen sechs speziellen Soziologien ihre Schwerpunktsetzung wählen. Nach 30 Jahren Soziologie-Studium in Marburg erschien es sinnvoll, Daten und Informationen über den Verbleib der bisherigen Absolventinnen und Absolventen zusammenzutragen. Dieser Aufgabe stellte sich eine Gruppe von Soziologiestudierenden im Grundstudium (2./3. bzw. 3./4. Fachsemester) zusammen mit ihrem Tutor und ihrer Dozentin im Rahmen eines über zwei Semester laufenden Empirischen Praktikums (Oktober 2003 bis Juli 2004). In Anlehnung an Verbleibs- und Studienabbruchs-Studien anderer Hochschulen wurden Fragestellungen für verschiedene Teiluntersuchungen und Erhebungsinstrumente entwickelt, Interviewtechniken trainiert, Daten erhoben und quantitativ bzw. qualitativ ausgewertet sowie der abschließende Forschungsbericht geschrieben. Die Grundgesamtheit wurde (wegen der schwierigen Adressrecherche) auf die Abschlussjahrgänge 1990 bis 2003 beschränkt. Durchgeführt wurden: eine postalische Fragebogenuntersuchung aller erreichbaren AbsolventInnen (realisiert 88 Befragungen); drei berufsbiografische Interviews mit AbsolventInnenen der Jahre 1991-1996-2001; vier perspektivische Leitfadeninterviews (problemzentriert) mit AbsolventInnen des Jahres 2003; zwei Leitfadeninterviews mit einem Abbrecher bzw. einem Studienfachwechsler; Experteninterviews mit potenziellen ArbeitgebervertreterInnen. Für die Analysen wurden je nach Datenstandard statistische Verfahren, qualitative Inhaltsanalyse oder sequenzielle Analyse eingesetzt. Die Befunde ermöglichen Einschätzungen hinsichtlich der damaligen Diplom- und Magisterstudiengänge in Marburg - hinsichtlich Bachelor- und Master-Studiengängen oder für andere Hochschulen müsste eine Studie entsprechend modifiziert werden

TNPs have robust T lineage potential.

<p>BM-derived MPPs, CLPs, TNPs and thymic ETPs were sorted from C57BL/6 mice and 500 cells of each population were cultured on OP9-DL1 cells in the presence of 1 ng/ml IL-7 and 5 ng/ml Flt3L. A) Cells were gated as CD4⁻CD8⁻ (DNs) and analyzed for expression of CD44 and CD25 at the indicated time points. One representative experiment out of 2 independent experiments is shown. B) Cells were analyzed for expression of CD4 and CD8 at the indicated time point. C, D) Quantification of data obtained from panel B. E) Relative expansion of cultures based on an input cell number of 500. Combined data of two independent experiments with 6 wells per experiment. Error bars indicate SEM.</p

Characterization of TNPs from BM and blood.

<p>Lineage depleted BM and blood cells from C57BL/6 mice were stained for lineage markers, CD27, CD135, CD117, CD127 and CD90. A) Gating strategy for the identification of TNPs in BM and blood. Representative data from 1 out of 4 mice (BM) and pooled cells from 10 mice (blood). B) Relative quantification of MPPs (lin⁻CD27⁺CD135⁺CD127⁻CD117^hi), CLPs (lin⁻CD27⁺CD135⁺CD127⁺CD117^+/low), TNPs (lin⁻CD27⁺CD135⁺CD127⁻CD117^−/lowCD90⁻) and CD90⁺ (lin⁻CD27⁺CD135⁺CD127⁻CD117^−/lowCD90⁺) candidate T cell precursors within lin⁻CD27⁺CD135⁺ cells. Combined data of 4 mice and 20 mice for BM and blood, respectively, from 2 independent experiments. Error bars indicate SEM.</p

TNPs do not efficiently differentiate upon intravenous transfer.

<p>BM derived MPPs, CLPs and TNPs from C57BL/6 mice were sorted and 20,000 cells were intravenously injected into non-irradiated <i>Il7ra</i>-deficient mice expressing CD45.1 or CD45.1 and CD45.2. Donor derived cells were analyzed in thymus and BM by FACS for the expression of CD45.1 and CD45.2 at A) 2 weeks and B) 4 weeks after transfer. One representative experiment out of four and three (2 weeks and 4 weeks, respectively) independent experiments with 2 mice each is shown. C) Combined analysis of frequencies of donor-derived thymocytes of 4 and 3 individual experiments 2 and 4 weeks after transfer, respectively. Error bars indicate SEM. D) CD4 vs. CD8 surface expression of donor-derived thymocytes 2 and 4 weeks after transfer. One representative experiment out of four and three (2 weeks and 4 weeks, respectively) independent experiments with 2 mice each is shown.</p

TNPs display limited non-T lineage potential.

<p>BM derived MPPs, CLPs, TNPs and thymic ETPs were sorted from C57BL/6 mice and 500 cells of each population were cultured on OP9 cells in the presence of 5 ng/ml IL-7 and 5 ng/ml Flt3L. A) Cells were analyzed for the expression of CD11c and CD11b at day 7 of culture. B) Cells were analyzed for the expression of CD19 and B220 at day 11 of culture. C) Relative expansion of myeloid cells after 7 days of culture (from 500 input cells). D) Relative expansion of B cells after 11 days of culture (from 500 input cells). C, D) Numbers above columns indicate fold expansion. E) TNP-derived cultures. Analysis was performed as in panel A) after 17 and 24 days. F) TNP-derived cultures. Analysis was performed as in panel B) after 17 and 24 days. A, B, E, F) One representative experiment out of 2 independent experiments is shown. C, D) Combined data of two independent experiments with 6 wells per experiment. Error bars indicate SEM.</p

TNPs do not efficiently differentiate upon intrathymic transfer.

<p>BM derived MPPs, CLPs and TNPs from C57BL/6 mice were sorted and 20,000 cells were intrathymically injected into non-irradiated CD45.1 mice or CD45.1/2 mice. A) Donor derived cells were analyzed in thymus by FACS for the expression of CD45.1 and CD45.2 at 3 weeks after transfer. B) Donor derived cells from MPPs, CLPs and TNPs were also analyzed for CD4 and CD8 surface expression for identification of DN (CD4⁻CD8⁻), DP (CD4⁺CD8⁺) and SP (CD4⁺ or CD8⁺) cells. C) Donor derived electronically gated DN cells from MPPs, CLPs and TNPs were analyzed for CD117 and CD25 surface expression for identification of DN subsets (DN1: CD117⁺CD25⁻; DN2: CD117⁺CD25⁺; DN3: CD117⁻CD25⁺). One representative experiment out of three independent experiments with 3 mice each is shown. D) Combined analysis of 3 experiments with each 3 mice per group. Error bars indicate SEM.</p